Hello,
I would like to use OPA1622 directly on output of high-end DAC using the following DAC-vendor-recommended circuit:
Are there any concerns with the component values in this circuit? I have read elsewhere that OPA1622 is sensitive to mis-matched input resistances due to relatively high input bias current.. is that a concern with this circuit?
Any other recommendations?
Here's the Tina-TI simulation:
Hey Evan,
If you happen to have the discussion on the "sensitivity" I can take a look. I don't see a concern here however due to the DC bias currents. High bias currents will create more ib on R error voltage and any mismatch can create what looks like a differential signal on the input to the amplifier. This would create a constant DC error. If the DC error is not acceptable in the application a high input impedance JFET amplifier is a good low noise alternative to bipolar input amplifiers. One such device is the OPA145. Impedance mismatch on the front end can impact the AC CMRR performance and this may be the sensitivity that you are referring to?
The bandwidth of this circuit is 131.9 kHz in a gain of 1.
The transient response looks good and I also ran a stability check and do not see any issues with stability.
Here is the Tina simulation I put together.
Let me know if I can be of further assistance.
Best Regards,
Chris Featherstone
